Table 4.

Usability problems identified in version 3 of all 3 self-tests and the rate of errors (n=20).

Problem ID	Usability problem	Rate of errors/trials
1	Incorrect performance	19/60 (32%)
2	Performed test (during instruction video) without starting the test in the app	5/60 (8%)
3	Did not sit still and wait for start signal after test was started in the app	0/40 (0%)
4	Incorrect placement of phone	0/60 (0%)
5	Did not hear/perceive instructions	2/60 (3%)
6	Accidentally cancelled the test	1/60 (2%)